Capital One Coding & Algorithms Interview Questions
Master your tech interview with our curated database of real questions from top companies.
Solve string merge and grid path tasks
Question Given two equal-length strings s1 and s2, create a new string by iterating i = 0 … n-1, comparing s1[i] with s2[n-1-i]: append s1[i]; if the ...
Automate Python Virtual Environment Setup on Linux Terminal
Scenario Shell script that automates Python virtual-environment setup on a Linux terminal during a tech interview Question Walk through the script lin...
Explain Python Virtual Environment Setup and Function Analysis
Scenario Technical screen where candidate and interviewer jointly walk through Python code snippets used in a data-science repository. Question Show h...
Explain Shell Script Line-by-Line for Data Science Workflows
Scenario Technical screening for a Principal Data Scientist: reviewing shell script and Python classes Question Explain, line by line, what the provid...
Solve matrix rotation and 1-D illumination
Question LeetCode 48. Rotate Image – rotate an n×n matrix 90° clockwise (extra space allowed). Find the point(s) with the maximum number of illuminate...
Optimize invites under capacity constraints
You have n donors (n up to 100,000). For each donor i you know: p_online[i] (probability of donating if emailed), a_online[i] (expected donation condi...
Design late-tolerant streaming window aggregator
You receive an unbounded stream of events: (event_time, user_id, category). Events may arrive up to 48 hours late and are not ordered by time. Design ...
Implement minimal-cost overtime/contractor allocation
You must cover H extra engineering hours this week at minimum cost using employee overtime and optional contractors. Each employee i has a maximum ove...
Debug and test a Python function in venv
Consider the Python snippet below. """ import math def accumulate(nums, start=0, cache={}): total = start for n in nums: if n % 2 == 0: nums.appen...
Fix failing tests and refactor code
You're given a small Python repo. After creating and activating a clean virtual environment, installing requirements, and running "pytest -q", two tes...
Refactor code and enforce robustness
Code Review and Refactor: Summing a CSV Column Context You are reviewing a short Python script that sums a numeric column from a CSV using pandas. You...
Implement 2D transforms and find max-lit point
Part A — 2D array transforms: Given an m×n integer matrix, implement the following in-place operations with clear function boundaries and complexity: ...
Solve four algorithmic coding tasks
You will solve four independent coding tasks: 1) Count equal-value pairs in an array: Given an integer array nums of length n, return the number of in...
Solve powers, phases, grid pops, and swaps
Solve the following four problems: 1) Count powers of k in an array: Given an array of positive integers nums and an integer k >= 1, return how many e...
Rotate matrix and find max lamp coverage
1) Square-matrix rotation with extra space: Given an n x n integer matrix, return a new matrix that is the 90-degree clockwise rotation of the input. ...
Explain Shell Script for Python Virtual Environment Setup
Scenario Shell script for setting up a Python virtual environment during a tech screen Question Explain what each line of the provided shell script do...
Critique Shell Script for Credit-Card Program Tech Round
Scenario Tech round for a new credit-card program: candidate is shown a 5-6 line shell script and asked to critique it Question What kind of file is "...
Critique and Test Python Preprocessing Utilities Effectively
Scenario Code review of Python preprocessing utilities (OutlierHandler and three Imputer classes) Question Summarize, at a high level, what the Outlie...
Validate Unit-Test Coverage and Identify Missing Scenarios
Scenario Tech round: reviewing an existing unit-test that exercises the class from Part 2 Question i) What does the current unit-test validate? ii) Li...